Abstract: A quadrifilar helix antenna is provided having a feedpoint for the antenna connecting to individual helical antenna elements. A capacitive network, distributed along the length of the antenna, constitutes a variable frequency shunting network. At each position a first capacitive structure, that may comprise a single capacitor or multiple capacitors in series, interconnects a first pair of opposite antenna elements; a second capacitive structure interconnects the second pair of opposite antenna elements. As an applied frequency increases, the capacitive structures progressively short the opposite antenna elements thereby electrically reducing the antenna length.

Abstract: To accurately and reproducibly set the angle of a hinge, especially a very small hinge, a precision hinge and angled mounting stops are provided. The device comprises a hinge joint having a fastener, such as a screw, connecting two bodies. A flat C-shaped mounting stop fits over the fastener and has two straight outer edges that contact each of the two bodies, respectively. The relative angle between the outer edges determines the set angle of the hinge.

Abstract: A demodulation system and method is used in a sensor system, such as a fiber optic sensor system, that senses optical signals and modulates a phase generated carrier having a carrier frequency &ohgr;c to form a modulated carrier. The modulated carrier is preferably undersampled at two times the carrier frequency (2&ohgr;c), thereby maximizing the sensors' demodulated bandwidth relative to the sensors' sampling frequency. The undersampled, modulated carrier is orthogonally demodulated by multiplying the modulated carrier by cos(2&ohgr;c(t0)) and sin(2&ohgr;c(t0)) to extract even and odd harmonic components of the signal of interest. The even and odd harmonic components of the signal of interest are further demodulated by taking the square root of the sum of squares of the even and odd harmonic components, normalizing the even and odd harmonic components, and differentiating, cross-multiplying and differencing the normalized even and odd harmonic components to recover the signal of interest.

Abstract: A device for sensing projectile velocity in an underwater environment is provided. The device includes a plurality of evenly spaced voltage coil members positioned in the path of a projectile. Each voltage coil member includes a support frame having an opening therein and a magnetic coil mounted on the support frame, and a sensing member connected to each support frame. The sensing member includes means for outputting a signal responsive to passage of the projectile through the voltage coil member, and a logic arrangement for determining a difference between passage of the projectile between adjacent ones of said plurality of voltage coil members throughout the run thereof, thereby determining a velocity of the projectile.

Abstract: An ultrasonic sparse imaging array includes a substrate of an acoustically absorptive material, through which extend a multiplicity of holes. Adhesive sheets, having selectively conductive regions, are fixed to a first side of the substrate, and are each disposed over a first end of one of the holes. Plano-convex shaped transducer elements, having a wide acoustic field of view, are disposed on each of the sheets, each of the sheets serving as a positive electrode and providing a mechanical and electrical connection between the substrate and a multiplicity of transducer elements. Plating is fixed to the first side of the substrate and covers each of the transducer elements and comprises a negative electrode. A conductive epoxy fills each of the holes and a power source is in electrical communication with the negative electrode.

Abstract: An array through a first to a second side of a three-sided junction, accessed remotely by a single mode fiber transmits a light pulse sequence to the array and receives sound modulated return light signals via the second to a third side of the junction. Within each hydrophone, butt coupled fiber joints form a continuous structure, encapsulated within a compressible plastic tube for mechanical stability. Tube volume expands and contracts linearly with variations in acoustic pressure thereby proportionally modulating the optical path therethrough. Each joint is a partial reflector reflects part of the incident light beam back via the second to third side of the junction to a posthydrophone compensating interferometer which compensates for path difference between equally spaced array joints; From the third side of the junction the reflections from the butt coupled fiber joints pass through a light detector and signal processor.

Abstract: A coil restraint device for a torpedo mounted dispenser of a torpedo assembly is disclosed. The torpedo assembly includes at least a torpedo body, a longitudinal propulsion shaft housed within the torpedo body, and a torpedo mounted dispenser connected to the longitudinal propulsion shaft at the aft end of the torpedo body. The torpedo mounted dispenser houses a wire payout coil and a flex hose surrounds the wire payout coil, a forward end of the flex hose being open and unrestrained. The coil restraint device includes a flexible band member having an inner surface, an outer surface, opposite ends, and opposing longitudinal edges. A strap is provided on the outer surface of the flexible band member, the strap having opposite distal ends extending beyond a length of the flexible band member.

Abstract: A target simulation system is used to simulate a target, such as a submarine, for testing of homing projectiles, such as anti-submarine warfare (ASW) torpedoes. The target simulation system includes a target portion having an impact structure and a plurality of acoustic reflectors spaced at a distance that simulates the spatial extent and acoustic highlights of the desired target. The target simulation portion is suspended at a predetermined depth within an underwater environment using one or more suspension assemblies. The suspension assemblies include one or more support floats that float on the surface of the water and suspension lines that extend from the respective support floats to the target portion. A reflector sail is coupled to a support float at one end of the target simulation system and captures the surface wind to apply a force to the target simulation portion.

Abstract: An apparatus to provide spike conduction and power supply isolation that is effective for a 60 Hz power supply operating frequency. The power frequency blocking circuit is practically implemented for a 60 Hz power supply operating frequency. The power frequency blocking circuit provides an equivalent impedance of 100 ohms at the 60 Hz operating frequency, and the power frequency blocking circuit equivalent impedance is on the order of 1-2 ohms at frequencies above 1000 Hz where spike conduction is required. The power frequency blocking circuit is placed between each power supply terminal and ground. The circuit is comprised of a parallel combination resistor and capacitor.

Abstract: An electrical connector includes a plug section having a body, and a receptacle section which is connected to the plug section. A collapsible seal is disposed within a circumferential groove formed in the plug section. The receptacle section has a cylindrical housing with a clamping ring for securely engaging and connecting the receptacle section to the plug section. Upon connecting the receptacle section to the plug section any hydrostatic forces present in the chamber between the receptacle section and the plug section causes the collapsible seal to collapse within the groove thereby providing a volume defined by the groove which receives fluid therein for preventing hydrostatic lock.

Abstract: The present invention relates to an improved magnesium semi-fuel cell which has a magnesium anode, a seawater/catholyte electrolyte, preferably containing acid to solubilize solid precipitates, and an electrocatalyst composed of palladium and iridium catalyzed onto carbon paper. The acid added to the electrolyte is preferably selected from the group consisting of sulfuric acid, hydrochloric acid, phosphoric acid, acetic acid, and mixtures thereof.

Abstract: The present invention provides a method utilizing a wavelet transform for improving and optimizing the visual display of image data at the time of viewing to provide enhanced information analysis capability for image analysis such as breast cancer screening and diagnosis. Through the use of an interactive software tool, the user displays both unprocessed and processed images simultaneously. The method also allows additional enhancement iterations resulting in better image reading and interpretation. In the case of digital mammography images, this technique allows suppression of background details and enhancement of selected features allowing additional diagnostic capability.

Abstract: A method is provided that increases fracture toughness and reduces brittleness of a semi-crystalline ferroelectric polymer material while substantially maintaining ferroelectric properties of the material. The material is heated in an inert oxygen-free atmosphere to a temperature above the material's Curie transition but below its melting temperature. The material is then irradiated with beta particles to provide a desired level of fracture toughness that substantially maintains ferroelectric properties of the material. In the case of poly(vinylidene fluoride-trifluorethylene), the heating temperature is just above the material's Curie transition temperature, the beta particles have an energy level of approximately 2.5 mega electron volts (MeV), and the radiation dose should not exceed approximately 50 megarads (Mrads).

Abstract: A system and method is disclosed for a radar receiver, such as a wideband crystal video early warning receiver, to automatically detect the noise level of the radar receiver with immunity to high pulse repetition frequencies and high duty cycle signals. The noise riding threshold circuit utilizes high frequency components of the noise and, to the attenuated extent present, high frequency components of the video signal to produce the noise riding threshold voltage. An amplifier gain control permits adjusting the noise-riding threshold to a fixed relative level. In a preferred embodiment, the noise riding threshold control of the present invention utilizes current feedback amplifiers for wide bandwidth, high gain video amplifiers.

Abstract: A radially pressure balanced floating seal system is used to seal a rotating shaft, such as a drive shaft in a torpedo, or other type of vehicle or machinery. The radially pressure balanced floating seal includes an outer seal housing and an inner seal housing that floats with respect to the outer seal housing. The outer seal housing is secured proximate the shaft bearings, for example, in the tail cone of a torpedo. The inner seal housing is secured within an internal recessed region in the outer seal housing, and two or more discrete torque members or one distributed torque member extend from the outer seal housing to the inner seal housing to prevent rotation of the inner seal housing while allowing movement generally in a radial direction. The inner seal housing includes a lubricant recess formed within an internal annular aperture of the inner seal housing for containing lubricant. Double canted O-rings are disposed on each side of the lubricant recess in double canted O-ring grooves.

Abstract: A compact floating seal system for sealing a rotating shaft within a structure. The floating seal system has a cylindrical outer seal housing positioned within the structure with a cylindrical internal recessed region formed in the outer seal housing and a retaining flange extending into the internal recessed region. An axial retaining means axially retains the outer seal housing against the structure, and an outer torque member prevents rotation of the outer seal housing with respect to the structure. An inner seal housing is retained within the internal recessed region and abuts the retaining flange for preventing axial movement of the housing. The inner seal housing has a shaft aperture therethrough. First and second sealing member retaining grooves formed within the shaft aperture retain O-rings. A lubricant recess is formed within the shaft aperture between the grooves.

Abstract: A method for finding a probability density function (PDF) and its statistical moments for a chosen one of four newly derived probability models for an arbitrary exponential function of the forms g(x)=&agr;xme−&bgr;xn, −∞<x<∞; g ⁡ ( x ) = α ⁢   ⁢ x m ⁢ ⅇ - βx n , 0 ≤ x < ∞ ; g ⁢ ( x ) = α ⁡

Abstract: A method is disclosed for evaluating and/or selecting sonar systems and sonar sensors is provided that results in a performance rating that represents both the magnitude and consistency of detection of targets positioned at different depths. In a preferred embodiment wherein a sonar system includes at least one source and at least one receiver, the performance rating related to target detection, is plotted for each of a plurality of source and receiver depths. A dynamic range sensitivity factor is selected that provides sensitivity in the performance rating with respect to consistency of the detection range at different depths. The dynamic range sensitivity factor is preferably selected between zero and an inverse of a scaling factor related to a maximum detection range and a minimum detection range for a particular source and receiver depth relationship.

Abstract: A Submarine Horizontal Launch TACTOM Capsule (SHLTC) provides the capability for launching a Tactical Tomahawk (TACTOM) cruise missile from a horizontal torpedo tube on a submarine. The SHLTC completely encapsulates the TACTOM missile in the torpedo tube and is ejected from the torpedo tube with the TACTOM missile during launch. The SHLTC contains the TACTOM missile in a closure assembly to protect the TACTOM missile from damage. Following safe exit from the submarine, thrust from the rocket motor allows the TACTOM missile to break through a forward tearing shell of the SHLTC. The TACTOM missile and SHLTC completely de-couple and the SHLTC safely sinks away from the submarine and missile. The TACTOM missile continues up to broach the surface and transition to cruise mode.

Abstract: A muzzle door latch, or attachment mechanism, incorporates spring-loaded plungers acting within concave surfaces to provide additional resistance to vibration. The door, or cap, has an elastomeric seal about its outer circumference, which fits snugly within the muzzle. Diametrically opposed guides are attached to the outer side of the cap and extend radially past the outer edge of the muzzle. A plate is attached to the exterior of the muzzle, corresponding to each guide, and each plate extends slightly beyond the end of the muzzle. A roller on each guide engages the outer surface of the plate when the cap is positioned within the muzzle. The plates have a concave indentation on their inner surface, and a spring-loaded plunger on each guide is biased against the concave surface.